Electrical switch



Sept. 8, 1942. H. B. RUDD ELECTRICAL SWITCH Filed Dec. 23, 1938 2Sheets-Sheet 1 INVENTOR ATTORNEYS H. B RUDD ELECTRICAL SWITCH Sept. 8,1942.

2 Sheets-Sheet 2 \INVENTQR Filed Dec. 23, 1938 BY m/P/FVE E000.AT'fORNEYJ drawingainwhich: I

Batented Sept. 8, 1942 Y UNlTED STATES", PATENT OFFICE I. I Y 2,295,054uncritical. swrrcn Harry B; Budd, Flushing, N. Y. V meanti e-mm 23,1938, Serial No. 247,330

8 Claims.

My invention relate to electricalswitches of the delayed-action type.

My invention, in a prominent aspect, has reference to switcharrangements wherein mercury from a pool of mercury is caused to flowthrough a diaphragm or barrier passage having such small cross-sectionalarea that th mercury is incapable of flowing therethrough solely underthe influence of it'sgravitatlonal'head;

Myinvention, in other prominent aspects, re-

Y Figure l is a perspectiveview illustrating an application of myinvention"; i

Fig. 2 is a vertical sectional view, partly in elevation, showing theswitch andswitch housing of my invention I Fig. 315 a transverseverticai sectional view, partly in elevation,-t'aken on the lipeH ofFig. 2 looking, in, the direction of the arrows;

FlgAis-a vertical'sctional view, partly in elevation, showing th switchof my invention in one of'its positions;

Fig. .5 is a vertical sectional viempartly in elevation, showing theswitch ofmy invention in its normal position; c

Fig. 6 is a horizontal sectional view, partly in plan, taken on the line6--6 of Fig. 2 looking in the direction of the arrows; Fig. 7 is anenlarged sectional view showing a barrier as constructed in. accordancewith my invention;

Fig. 8 is a vertical sectional view, partly in elevation, showing acombined toasterand switch arrangement;

Fig. 9 is an end elevational view of the ar-- rangement shown in Fig. 8;v

Fig. 10 is a vertical sectional view, partly in 8 accompanying Referringparticularly to Figs. 25 inclusive, A represents a sealed envelope orswitch casing formed from any suitable material such, for example, asglass, a phenol condensation product or the like. As herein shown, thecasing A comprises a pair of spaced tubular sections a, a shaped so asto form inner and outer passages I or chambers b, b preferably ofarcuate configuration or substantially so and arranged. preferably, inconcentric relation with respect to each other. The casing A defines anend passage or chamber d by which adjacent ends of the passages orchambers b, b are placed in communication within each other. The casingA also defines another end passage or chamber 1 by which the otheradiacent'ends of said passages or chambers b, b

.are placed in communication with each other.

I As "shown in Figs. 4 and 5, the inner surface of the inner casingsection a is shaped to form a horizontal ledge g which is disposed atthe Junetion between'ithe inner} passage or chamber b and the chamber1'.

As'shown in Figs. 4 and 5, the casing end chambersd and {may haveassociated therewith the respective switch contact members i and 1 whichextendthrough and are sealed to the casing wall, the inner ends of thesecontact members being adapted to physically contact with anelectricity-conducting medium disposed interiorly of the casing A andthe outer ends of said contact members being adapted to be connectedelevation, showing another form of switch: and

Fig. 11 is a transverse vertical sectional view, partly in elevation,taken on the line |Ill of Fig. 10 looking in the direction of thearrows.

in an electrical circuit, for example, as hereinafter described."

In accordance with the invention, the casing A should be mounted foroscillatory movement on a fixed axis and, to this end, an arrangement ofany suitable character may be utilized. Thus, as shown, a pair of,clamping members I, i may be suitably flxed to said casing A, as by abolt 2 l and nut 2a coactable therewith, the bolt 2 extending betweenthe casing-sections a, If Transversely fixed to the clampingmembers I, Iis'a shaft 3 which may bejournaled for oscillatory movement in thespaced arms In of a bracket 4 having its base suitably secured to asupport" 5 which, in one form of the'invention, may carrya housing 6forming an enclosure for the casing A and associated parts,

Exteriorly of the housing 6, when utilized, the haft 3 may hav a pointerI and an actuating knob '8 fixed thereto, the pointer l coacting with ascale 9, Fig, l, and the motion of said pointer I in one direction beinglimited by a stop member I0, or equivalent, fixed, in the example shown,

5.3 to the adjacent surface of the housing 6.

Obviously, with the form of the invention shown in Figs. 1-6 inclusive,the stop member In coacts with the pointer I to define the limit ofoscillatory movement of the shaft 3 and the thereby-carried casing A ina counter-clockwise direction, Fig. 5. Preferably, the casing A isbiased constantly toward the position thereof shown in Fig. 5 and, tothis end, for example, there may be utilized a spring I! which is coiledaround the shaft 3, one end of said spring l2 being secured to one ofthe clamping members i and the other end thereof being secured to theadjacent standard arm in. When the shaft 3 and casing A are moved in aclockwise direction, Fig. 5, energy is stored in the spring l2 and,accordingly, said casing A constantly tends to return to the positicnthereof shown in Fig. 5.

In accordance with the invention as illustrated in Figs. 1-5 inclusive,the casing A contains a suitable quantity of mercury material or othering end passage or chamber f. This diaphragm k is sealed throughout itsentire outer edge surface to the adjacent casing surface defining saidlast named passage or chamber b so that the flow of mercury through thejuncture thus formed is prevented in a positive manner.

The aforesaid barrier k is provided with a passage kl through whichmercury is caused to flow. In accordance with the invention, thecross-sectional area of this passage kl, or its diameter if circular, isso small that mercury from a pool of mercury confined in part by saidbarrier k is incapable of flowing therethrough substantially as auniform stream under the influence of its head unless the surfacetension effect of the mercury in or at said passage kl is overcome.Thus, as shown in Fig. 7, the cross-sectional area .of the passage kl isso small that the head of mercury in the pool thereof at the right ofthe barrier k is incapable of breaking the surface tension of themercury in said passage kl to an extent sufficient to insure a uniformflow of mercury through said passage kl.

This surface tension effect of the mercury in the passage kl is overcomein a novel manner,

in accordance with the invention, 50 that the de sired uniform flow ofmercury is obtained. Thus,

in Fig. 5. I have shown the casing A in its normal attain a common levelunless in the meantime mercury is transferred to the pool at the rightof the barrier k by clockwise movement of the casing A on its axis.

With the casing A positioned as shownin Fig. 5, the electrical circuitin which the contact members i and j are included is closed by thecolumn of mercury in the inner passage or chamber b. While said casing Aremains stationary in the position shown in Fig. 5, mercury, under theinfluence of the head of said column of mercury, flows from right toleft as a substantially uniform stream through the barrier passage kl.Eventually, the top surface of the mercury in the end chamber 1 descendsto such extent that said top mercury surface, separates or breaks at theledge g whereby said electrical circuit is opened in the pool of mercuryand not by recession of the mercury from the contact member 7'. Thiscompletes the circuit-opening operation although, if the casing Acontinues to remain stationary, the two mercury pools will reach acommon level. I

At any time after the aforesaid circuit has been opened, the knob 8 maybe actuated against the action of the spring l2 to thereby rotate thecasing A in a clockwise direction to the position illustrated in Fig. 4,for example. By so doing, mercury is transferred, under the influence ofgravity, through the separate passages or chambers b, b'so that itreturns to the casing end chamber f. Immediately thereafter, the casingA is returned counter-clockwise to its normal position as shown in Fig.5 and as defined by the stop member I0. During such return movement ofthe casing A, there is no transfer of mercury through the outer passageor chamber ball of the transferred mercury congregates in the innerpassage or chamber b and in the casing end chamber j. Accordingly, assaid casing A returns to normal position as described above, thetransferred mercury again closes the circuit between the contact membersi and 7'.

When the .casing A is in the position shown in Fig. 4, it will be notedthat pools of mercury remain in contact with the respective oppositesides of the barrier k. This is an inventive feature of importancebecause, by so doing, the surface tension effect illustrated in Fig. 7may not be established. If necessary, a suitable stop member, not shown,may be provided to prevent such excessive clockwise rotation of thecasing A from the position thereof shown in Fig. 4 that would result indraining the mercury from one or both sides of the barrier k.

It will be noted that the outer passage or chamber b is of curved orarcuate configuration. This is a feature of importance because, by soshaping said outer passage or chamber b, desired different quantities ofmercury may be transferred therethrough with accuracy so that thecircuit through the contact members i and 7' may remain closed forselected different periods of time. Thus, the scale 9 shown in Fig. 1indicates different positions which the casing A may take when mercuryis transferred through the outer passage or chamber b in the mannerdescribed above. By properly calibrating said scale 9, it follows thatthe operator may move the pointer ID to a scale mark indicative of adesired period of closure of the contacts 1' and j.

.The delayed-action switch of my invention is capable ofmanyapplications and, as illustrative of one of such applications, Ihave indicated in Fig. 1 a circuit arrangement whereby said switchcontrols the circuit of a conventional electrical toaster 20 providedwith the usual grid-shaped heating element 2| included in the circuit ofa pair of conductors in the cable 22, these conductors terminating inthe respective prong contacts of a conventional plug 23. As illustratedin Fig. 2, the aforesaid support 5 for the switch casing A may carry asocket 24 to which extends the conductors 25 and 23 secured,respectively, to the switch contact members i and 1. Extending from thesocket 24 is a cable 21 comprising a pair of conductors adapted to beassociated with the respective conductors of a suitable line circuit 23.It will be understood that the arrange-. ment is such that, after theplug of the cable 21 has been associated with the line circuit, the plug23 may be associated with the socket 24 to thereby connect both sides ofthe line circuit to the terminals of the grid element 2i, one side ofthe line including the switch contact members i and 9' in seriestherewith.

slices of bread may be disposed in the toaster 20 and the knob 8 rotatedin a clockwise direction to a desired scale indication, the'scale, inthis instance, preferably being calibrated in terms of light, medium,and well done" toast. When the knob 8 is rotated as just described, theswitch casing A is likewise rotated to thereby transfer a desiredquantity of mercury into the end chamber 1. While the knob 8 is beingreturned to its original position, as defined by the stop member II),the switch casing A partakes of similar return movement with the resultthat the circuit through the grid element 2| is closed, such circuitremaining closed until opened by separation of mercury along thehorizontal ledge g of the casing A.

In Figs. 8 and 9, I have illustrated another application of my inventionrelating to the breadtoasting art. As shown, a toaster 30, generally ofconventional design, comprises a base 3| and a casing 32 secured theretoand upstanding therefrom. 'Within the casing 32, the grid-shaped heatingelement 33 may be supported in suitable manner, one end of this gridelement terminating in a contact member 34 and the other end thereofterminating in a contact member 35. The cable 36 which is adapted to beassociated with the line circuit comprises a pair of conductors 31 and38, the conductor 31 being connected to the contact member 34 and theconductor 38 leading either to the switch contact member 1' or the otherswitch contact member being connected to the contact member 35 by aconductor 39. In this manner, the switch contact members i and 7' areincluded in series with one side of shaft 3 may be journaled in thecasing 40 and a bearing bracket 4| suitably secured to theadjacent wallof the casing 32.

In the example of the invention shown in Figs.

The bi-metallic structure 44 is shown in the position taken thereby whenthe toaster is in its non-heated condition. When the knob 3 is actuatedto prepare toast, thepositicn to which it should be moved may bedetermined by observation of the pointer I and thescale on the plate 42.This operation of preparing toast causes the bi-metallic structure 44 tomove upwardly "and, by the link 43, the scale-bearing member is movedslightly in a counter-clockwise direction, Fig. 9. Accordingly, iffurther toast is immediately prepared, the operator moves the pointer lto the proper scale indication but, by reason of the describedcounter-clockwise movement of the scalebearing member 42, a slightlysmaller quantity of mercury is transferred along the path therefor inthe casing A. In this manner, compensation is effected for the heatedcondition of the toaster. Obviously, when the toaster again becomescool, the bi-metallic structure 44 is in the position shown and thescale-bearing member 42, likewise, is in its original position.

It will be understood that within the inventive idea of the arrangementof Figs. 8 and 9, the scale-bearing member 42 may be mounted in fixedposition and compensation may be efiected for the heated condition ofthe toaster by causing the bimetallic structure 44 to impart slightmovement to the switch casing A. With respect to Figs. 14 inclusive, Ihave hereinbefore described a switch of one form as constructed inaccordance with the invention. It shall be understood that the novelswitch of my invention may take a variety of other forms and, in Figs.10 and 11, I have illustrated a present preferred switch differing fromthe one hereinbefore described.

Thus, in said Figs. 10 and 11, I have shown a sealed switch casing Aiwhich may be constructed of suitable material, for example, ashereinbefore described, said casing l containing a body of mercury M.The casingAl comprises a horizontal chamber section m and a dependingcurved chamber section n. Communicating with the chamber section m are apair of spaced contact members 0 and p which, when the casing is innormal position as illustrated in Fig. 10,, terminate below a ridge qextending horizontally across said horizontal chamber section m.

Adjacent the juncture between the horizontaland depending casingsections 1n and 11., there is a barrier or diaphragm r sealed to theadjacent casing surface and having a passagef/rl extending 8 and 9, thepointer 9 coacts'with a scale formed on a plate 42 which is movable todifferent positions depending upon the temperature conditions interiorlyof the toaster 30. As illustrative of one form of movable scalearrangement, I-have shown the scale-bearing member 42 as looselysupported on the shaft 3, Figs. 8 and 9. Secured to and depending fromthe scale-bearing member 42 is a link 43 which, at its lower end, isconnected to a bi-metallic structure 44 suitably positioned within thecasing 32 so as to be affected by the heat transmitted thereto from theheating element 33. As herein shown although notnecessarily, thebimetallic structure 44 is disposed just above the top wall of the base3| and one end of said bimetallic structure 44 is suitably secured tosaid base 3i, as by the bolt 45 and nut 45a.

therethrough. At the side 'of the diaphragm removed from the chamber inwhich the switch contacts 0 and p are received, the casing is shapedupwardly as indicated at s. The barrier r comprises a downwardlyextending section r2 utilizableas hereinafter described.

It shall be understood that the casing Al of Figs. 10 and 11 will haveassociated therewith a clockwise rotation of the chamber Al causing thetransfer of mercury from the depending casing.

chamber 71 to the horizontal casing chamber m along a path extendingabove the barrier r, or

through a passage in said barrier in case the lat ter extends entirelyacross the casing AI. Therefore, as the casing Al is shown in Fig. 10,mercury cleanly condition.

flows substantially as a uniform stream through the barrier passage rlin a direction from right to left, such mercury first entering thechamber defined in part by the aforesaid casing section s and thendropping downwardly into the casing chamber n. Eventually, the uppersurface of the pool of mercury in the casing chamber m separates at theridge q to thereby open the circuit to which the contact members and pare connected.

The cross-sectional area of the barrier passage rl is of the samegeneral value as hereinbefore described with respect to the barrierpassage kl of the barrier is. That is, mercury from the pool of mercuryshown in the casing chamber m is incapable of flowing through saidbarrier passage sl under the influence of its gravitational head unlessthe surface tension effect of the mercury in or at said passage rl isovercome. In order to overcome the effect of surface tension in thebarrier passage rl, I provide, in accordance with the invention, thechamber defined in part by the aforesaid upwardly extending casing walls. As indicated in Fig. 10, this chamber last named serves as areservoir containing a pool of mercury which covers the exit side of thebarrier passage rl.

During clockwise rotation of the casing Al from the positionthereof'shown in Fig. 10, the depending section r2 of the barrier rserves to entrap the mercury contained in the chamber defined in part bythe aforesaid casing wall s, the exit side of the barrier passage rlbeing uncovered by the mercury which moves into the space defined bysaid depending barrier section 12. However, as the casing Al is returnedcounterclockwise to its normal position, the mercury thus entrappedreturns to its chamber at the left of the barrier rand effectivelyprevents the development of any surface tension effect at the barrierpassage r2 which would prevent passage of the mercury therethroughsubstantially as a uniform stream.

With respect to the forms of my novel switch as disclosed, the passageof the mercury through the barrier passage serves to lower the level ofthe mercury pool into which the switch contacts extend so that thecircuit connected to said switch contacts may be opened. It shall beunderstood that, as well, the arrangement may be such that the mercury,as a result of the passage thereof through the barrier passage, servesto close a circuit rather than open the same. Thus, for example, withthe switchshown in Figs. and 11, it will be understood that the switchcontact member 0, for example, may be removed from the position shownand mounted so that it extends into the depending casing chamber n at aproper level above the bottom thereof.

As hereinbefore stated, the casings A and Al are sealed. Preferably,before this sealing operation, the switch casings of my invention havethe atmospheric air evacuated therefrom, such air being replaced by asuitable inert gas such, for example, as hydrogen gas which serves toquench the spark and to keep the mercury in a Ordinarily, it isdesirable for this inert gas to have a pressure exceeding atmosphericpressure by several pounds.

The hereinbefore described barriers or diaphragms may be formed from anysuitable material which is non-combinable with mercury such, forexample, as nickel, stainless steel, or equivalent. These diaphragms orbarriers necessarily are relatively thin particularly in the areathereof provided with the passage to be traversed by mercury. It hasbeen demonstrated in practice that the thickness of the barrier may beof we order of 0.002 of an inch and that the diameter of the passages klor rl therethrough may be of the order of 0.010 of an inch. It shall bedistinctly understood that my invention is not to be limited in theserespects. Thus, the thickness of the diaphragm or barrier may varywithin rather wide limits and the same is true of the cross-sectionalarea of the diaphragm or barrier passages kl and rl. With respect to thelatter, it will be understood that my invention relates to a conditionsuch as shown in Fig. 7 wherein the gravitational head of the mercurypool is incapable of breaking the surface tension existing at thebarrier passage so as to cause uniform flow of the mercury.

It shall be understood that the delayed-action switches of my inventionmay be of such character that a constant quantity of 'mercury istransferred from one side of the barrier to the other when effecting there-setting operation by rotatable movement applied to the switch casing.With this arrangement, the various control periods are of the samfevduration. This is a desirable feature in connection with someapplications of the invention.

Although I have illustrated and described the novel switch of myinvention as utilizable in a particular art, namely, the bread-toastingart, it shall be distinctly understood that my invention, by no means,is-to be thus limited. The delayed-action switch of my invention iscapable of use as a control for a large variety of electrical circuits.That is, the novel switches of my invention may be utilized for timingpurposes generally such, for example, as the timing of camera exposures,photo-composing machine exposures, traffic lights, other electricalapparatus, etc., etc.

A particularly important advantage of my invention resides in the factthat my switch comprises a diaphragm or barrier passage havingcross-sectional area so small that the mercury is incapable of flowingtherethrough under the influence of its head unless the surface tensioneffect of the mercury in or at said passage is overcome. Accordingly,even though the switch comprises a relatively small quantity of mercury,the operation thereof may be delayed over relatively long periods oftime. The switches of my invention, then, are of lighter weight,smaller, require less mercury, etc. than do prior art delayed-actionswitches.

While the invention has been described with respect to certainparticular preferred examples which give satisfactory results, .it willbe understood by those skilled in the art after understanding theinvention, that various changes and modifications may be made withoutdeparting from the spirit and scope of the invention and it is intendedtherefore in the appended claims to cover all such changes andmodifications.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a switch of the character described, a casing, a body of mercuryin said casing, and a barrier secured interiorly of said casing to formside-by-side chambers therein, said barrier being provided with apassage through which mercury may flow and the' cross-sectional area ofsaid passage being so small that mercury is capable of flowingtherethrough as a substantially-uniform stream only when there are poolsof mersponse to movement of said casing on its axis,

said casing being selectively movable on its axis diiierent' distancesfrom the normal position thereof whereby diflerent respective quantitiesof mercury may be passed along said path, and means for passing mercuryin reverse direction between said chambers, said means comprising adiaphragm passage having a cross-sectional area so small that mercury iscapable of flowing therethrough as a substantially uniform stream onlywhen there are pools of mercury on the respective opposite sides of thediaphragm which cover both sides of said passage.

3. In a switch of the character described. a casing having a normalposition, means forming an axis on which said casing is mounted foroscillatory movement, a body of mercury in said casing, said casinghaving therein a plurality of chambers joined by a path for passingmercury from one chamber to the other chamber in re-t sponse to movementof said casing on its axis, said casing being selectively movable on itsaxis diflerent distances from the normal position thereof wherebydifferent respective quantities may be passed along said path, said pathcomprising a curved section serving to facilitate regulation of thequantity of mercury I thus passed along said path, and means for passingmercury in reversedirection between said chambars, said means comprisinga diaphragm passage having a cross-sectional area so small that mercuryis capable of flowing therethrough as a substantially uniform streamonly when there are pools of mercury on the respective opposite sides ofthe diaphragm which cover both sides of said passage.

HARRY B. RUDD.

